1// SPDX-License-Identifier: GPL-2.0
2/*
3 * sgi_w1.c - w1 master driver for one wire support in SGI ASICs
4 */
5
6#include <linux/clk.h>
7#include <linux/delay.h>
8#include <linux/io.h>
9#include <linux/jiffies.h>
10#include <linux/module.h>
11#include <linux/mod_devicetable.h>
12#include <linux/platform_device.h>
13#include <linux/platform_data/sgi-w1.h>
14
15#include <linux/w1.h>
16
17#define MCR_RD_DATA	BIT(0)
18#define MCR_DONE	BIT(1)
19
20#define MCR_PACK(pulse, sample) (((pulse) << 10) | ((sample) << 2))
21
22struct sgi_w1_device {
23	u32 __iomem *mcr;
24	struct w1_bus_master bus_master;
25	char dev_id[64];
26};
27
28static u8 sgi_w1_wait(u32 __iomem *mcr)
29{
30	u32 mcr_val;
31
32	do {
33		mcr_val = readl(mcr);
34	} while (!(mcr_val & MCR_DONE));
35
36	return (mcr_val & MCR_RD_DATA) ? 1 : 0;
37}
38
39/*
40 * this is the low level routine to
41 * reset the device on the One Wire interface
42 * on the hardware
43 */
44static u8 sgi_w1_reset_bus(void *data)
45{
46	struct sgi_w1_device *dev = data;
47	u8 ret;
48
49	writel(MCR_PACK(520, 65), dev->mcr);
50	ret = sgi_w1_wait(dev->mcr);
51	udelay(500); /* recovery time */
52	return ret;
53}
54
55/*
56 * this is the low level routine to read/write a bit on the One Wire
57 * interface on the hardware. It does write 0 if parameter bit is set
58 * to 0, otherwise a write 1/read.
59 */
60static u8 sgi_w1_touch_bit(void *data, u8 bit)
61{
62	struct sgi_w1_device *dev = data;
63	u8 ret;
64
65	if (bit)
66		writel(MCR_PACK(6, 13), dev->mcr);
67	else
68		writel(MCR_PACK(80, 30), dev->mcr);
69
70	ret = sgi_w1_wait(dev->mcr);
71	if (bit)
72		udelay(100); /* recovery */
73	return ret;
74}
75
76static int sgi_w1_probe(struct platform_device *pdev)
77{
78	struct sgi_w1_device *sdev;
79	struct sgi_w1_platform_data *pdata;
80
81	sdev = devm_kzalloc(&pdev->dev, sizeof(struct sgi_w1_device),
82			    GFP_KERNEL);
83	if (!sdev)
84		return -ENOMEM;
85
86	sdev->mcr = devm_platform_ioremap_resource(pdev, 0);
87	if (IS_ERR(sdev->mcr))
88		return PTR_ERR(sdev->mcr);
89
90	sdev->bus_master.data = sdev;
91	sdev->bus_master.reset_bus = sgi_w1_reset_bus;
92	sdev->bus_master.touch_bit = sgi_w1_touch_bit;
93
94	pdata = dev_get_platdata(&pdev->dev);
95	if (pdata) {
96		strscpy(sdev->dev_id, pdata->dev_id, sizeof(sdev->dev_id));
97		sdev->bus_master.dev_id = sdev->dev_id;
98	}
99
100	platform_set_drvdata(pdev, sdev);
101
102	return w1_add_master_device(&sdev->bus_master);
103}
104
105/*
106 * disassociate the w1 device from the driver
107 */
108static int sgi_w1_remove(struct platform_device *pdev)
109{
110	struct sgi_w1_device *sdev = platform_get_drvdata(pdev);
111
112	w1_remove_master_device(&sdev->bus_master);
113
114	return 0;
115}
116
117static struct platform_driver sgi_w1_driver = {
118	.driver = {
119		.name = "sgi_w1",
120	},
121	.probe = sgi_w1_probe,
122	.remove = sgi_w1_remove,
123};
124module_platform_driver(sgi_w1_driver);
125
126MODULE_LICENSE("GPL");
127MODULE_AUTHOR("Thomas Bogendoerfer");
128MODULE_DESCRIPTION("Driver for One-Wire IP in SGI ASICs");
129